Trench power MOSFET devices are used in many applications including power supplies, battery chargers, computers, and cell phones. An important aspect to a trench power MOSFET device is its channel density and on-state resistance (RDS(ON)). An increase in channel density decreases RDS(ON). A lower RDS(ON) results in a reduction in the total resistance encountered by a drain current flowing from the drain terminal to the source terminal of the power MOSFET device.
Trench power MOSFET devices have a source contact region, and an inter-layer dielectric (ILD) on the top surface of the device which requires a relatively large spacing between the device trenches. A large spacing between trenches limits the cell density of the device. Further reduction in cell size typically requires advanced manufacturing schemes thereby increasing device cost. The limit in the cell density also limits a reduction in RDS(ON).
Thus, a need exists for a trench power MOSFET device that has an increased cell density thereby reducing RDS(ON) of the device.